Method of preloading a ball joint seat assembly



Dec. 28, 1965 s, SULLIVAN, JR 3,225,420

METHOD OF PRELOADING A BALL JOINT SEAT ASSEMBLY Original Filed Oct. 22, 1962 4 INVENTOR.

Leo 8. 8ulliv0n,J/:

His Attorney United States Patent This is a division of copending application Serial Number 232,165Sul1ivan, filed October 22, 1962, belonging to the assignee of the present invention.

This invention relates to a method of preloading a ball joint seat assembly.

Another object of this invention is to provide a method of preloading a ball joint seat retainer assembly to increase bearing capacity thereof and simultaneously providing wear compensation by steps of tapering an outer periphery of one end of a ball seat having a curved inner periphery at an opposite end thereof, radially slitting the ball seat longitudinally along said tapering location, heating the ball seat to a predetermined temperature to increase ductility thereof, snapping the ball axially into place with an integral stud thereof projecting away from said tapering, pressing the ball and seat into a socket-like recess while simultaneously urging radially inwardly the outer tapering peripheral end of the ball seat into the preloading, increased bearing capacity and wear compensating condition, and finally covering the socket-like recess at a location remote from the stud projecting therefrom.

A further object of this invention is to provide a method of preloading a ball joint seat retainer assembly to increase bearing capacity thereof and simultaneously providing Wear compensation by steps of tapering an outer flared peripheral end of a ball seat having a curve-d inner periphery at an opposite end thereof, radially slitting alternate deep and shallow slots into the ball seat longitudinally along said tapering location, heating the ball seat to a predetermined temperature such as in oil at substantially 180 F. to increase ductility thereof, snapping the ball axially into place with an integral stud thereof projecting away from said tapering, pressing the ball and seat into a socket-like recess while simultaneously urging radially inwardly the outer tapering flared peripheral end of the ball seat into the preloading, increased bearing capacity and wear compensating condition, and finally covering the socket-like recess at a location re mote from the stud projecting therefrom.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a partially sectioned View of a ball joint seat assembly in accordance with the present invention.

FIGURE 2 is a cross-sectional view taken along line 2-2 in FIGURE 1.

FIGURE 3 is an end view of a ball seat per se having features in accordance with the present invention.

FIGURE 4 is a cross-sectioned elevational view taken along line 44 in FIGURE 3.

3 Claims.

"ice

FIGURE 1 is a partially sectioned View of a ball joint seat assembly generally indicated by numeral 10. The assembly 10 as illustrated in both FIGURES l and 2 includes a laterally extending threaded stud 11 adapted to be secured as a vehicle linkage tie rod end. The threaded stud 11 is integral with a housing portion 12 as seen in FIGURE 2. The housing portion 12 includes a cylindrical cavity 13 therein that communicates with an axial passage or opening 14 extending therefrom as shown in FIGURE 2.

A bellows-like resilient boot member 15 can have a flanged end 16 thereof fitted peripherally over a shoulder 17 of the housing portion 12 such that a spring metal clamping means 18 With radially outwardly projecting free ends 19 can be in snap-fit tight engagement for anchoring therewith. An expansion spring means 20 can be provided to urge the boot member 15 upwardly as indicated in FIGURE 2 and a radially inwardly pro- -ecting seal end 21 of the boot means can engage a conically tapered stud means 22 carried by a ball or curved head portion 24 chromed for corrosion resistance. Additional corrosion resistance can be provided by packing the assembly with a suitable lubricating material retained by the bellows-type dirt-shielding boot sealing member 15. Such lubricant packing can be provided initially during manufacture and no further lubrication is to be required during service and operation of the subject ball joint seat assembly as a result of an improved ball seat per se generally indicated by numeral 30 in views of FIGURES 2, 3 and 4.

The ball seat per se includes an annular body 31 of low-friction resilient material having a curved inner periphery 32 at one end as well as an outwardly flared opposite end 33. The diameter of the cylindrical cavity 13 of the housing portion 12 is less than outer diameter of the outwardly flared flange end 33. The low-friction resilient material for the ball seat per se 30 can consist of a compounding of Delrin acetal resin with Teflon fluorine-containing tetrafluoroethylene fibers mixed together for both resiliency and moldability. The fluorinecontaining fibers eliminate need for periodic lubrication.

In the ball seat per se there can be provided a plurality of cuts or slits at least some of which extend from one end into the curved inner periphery 32. In the embodiment shown in views of FIGURES 2, 3 and 4 of the drawings, there are radial slits of alternately deep and shallow configuration located axially in the ball seat and extending longitudinally from the flared flange end 33 thereof. As indicated in FIGURE 4, there can be deep slitting 34 as well as shallow slitting 35 alternately at predetermined locations such that a plurality of segments 36 are formed therebetween and are adapted to be displaced radially inwardly as permitted by the slitting 3435 for preloading as well as Wear-compensating purposes. It is to be noted that alternate deep and shallow slitting can be located at diametrically opposite locations as shown in FIGURE 3 such that the segments 36 therebetween have one end integral with the annular body 31 providing therewith an integral ball seat and retaining means for the curved head portion 24 as indicated in FIGURE 2.

Essential for the present method of preloading the ball joint seat retainer assembly to increase bearing capacity thereof and simultaneously providing wear compensation, the following steps are included during manufacture of the ball joint seat assembly. These steps include tapering the outer flared peripheral end 33 of the ball seat per se having the curved inner periphery 32 at an opposite end thereof. Then there is radial slitting of alternately deep and shallow slots 3435 into the ball seat per se longitudinally along the tapering location. This tapering on the outside of the ball seat starting at a location to one side of the spherical or curved inner periphery 32 permits preloading of the ball or curved head portion 34 therewith. This tapering combined with the radially and longitudinally extending slots or slits in the seat per se can be effective in causing at least part of the body portion 31 having the spherical or curved inner periphery thereof to be forced radially onto the ball or curved head portion once the ball seat and headed stud as assembled to each other are pressed into the ball joint housing, such as for a tie rod and retainer assembly. Additional preloading is accomplished by the angle along the outwardly flared end to place the segments such as 36 in a bending attitude due to provision of the radial slots or slits 3435 in the ball seat.

Assembly of the stud and head portion into the seat is accomplished by a step of heating the seat per se in a hot liquid medium such as oil, water and the like at a temperature of substantially 180 F. to increase ductility of the resin material of the ball seat per se followed by snapping the ball or curved head portion 24 into place relative to the curved inner periphery 32. Use of oil for heating the seat per se 30 can be advantageous since this will provide a preliminary lubrication for both inner and outer surfaces thereof to facilitate press fitting of the combined ball and seat assembly into confines of the cylindrical cavity 13 having the diameter thereof less than that of the outwardly flared peripheral end 33. As can be seen in FIGURE 2, the ball seat with the curved head portion 24 therein is assembled to the housing portion 12 such that the stud 22 projects through the opening 14 and is engaged by the sealing end 21 of the boot member. The outwardly flared end 33 is forced radially inwardly such that the segments 36 provide preloading as well as wear compensation and resilient retention of the curved head portion 24 inwardly thereof.

A final step of covering the socket-like recess or cylindrical cavity 13 occurs by attachment of a plug or centrally embossed cover means 37 against the periphery end 33 subject to spinning or peening over a flange 38 radially inwardly and integrally with the housing portion 12 as shown in FIGURE 2.

It is to be noted that use of a circular wave or marcel spring for axial bias per se can be provided centrally as to the embossed cover means 37 though use of any spring axially of the opposite ends of the ball seat per se would not provide the radially inward preloading as permitted by the outwardly flared tapered end having the slots or slits radially and extending longitudinally thereof for elimination of looseness previously encountered after use of a vehicle for a relatively low mileage. Repeated lubrication is avoided for life of a steering linkage due to use of Delrin acetal resin with Teflon polytetrafluoroethylene fibers chopped and mixed into the composition molded to have the annular body and integral outwardly flared end with slots or slitting therein to provide both preloading as well as self-adjusting features for wear takeup.

As can be seen best in FIGURE 4, the tapered end projects outwardly by an angle of at least as represented by an are A as well as downwardly by an angle of at least as represented by an are E and an opposite conical ending 39 having an angle of substantially from the cylindrical outer periphery of the body 31 can be provided. When the ball seat per se 30 is installed in a socket as represented in FIGURE 2, it is apparent that then the tapered end is forced radially inwardly by at least 5 leaving a difference between the arcs A and B due to the inward bending with a resultant 5 downward projection of the lower periphery of the tapered end. This 5 resultant difference assures added preloading of the tapered portion due to engagement of this tapered end by the periphery of the cover 37 as indicated in FIGURE 2 thereby adding a preloading which assures maintenance of the segments such as 36 in a bending attitude for wear take-up simultaneously with the preloading. Preloading the ball or curved head portion 24 by use of the ball seat per se 30 also increases bearing capacity while simultaneously providing a means of wear compensation as well as resilient retention of the composition bearing material between the head portion 24 and housing portion 12.

While the embodiments of the present invention as herein disclosed constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A method of preloading a ball joint seat retainer assembly to increase bearing capacity thereof and simultaneously providing wear compensation by steps of outward tapering of an outer periphery of one end of a ball seat of acetal resin with fluorine-containing fibers mixed therein having an external cylindrical shape with tapered enlargement and a curved inner periphery at an opposite end thereof, radially slitting the ball seat'longitudinally along said outward tapering location, heating the ball seat of acetal resin with fluorine containing fibers mixed therein to a predetermined temperature to increase ductility thereof, snapping the ball axially into place complementary to the curved inner periphery with a stud carried by the ball in a location remote from said outward tapering, pressing the ball and seat into a socket-like recess having a diameter less than that of the outer periphery due to said outward tapering while simultaneously urging radially inwardly the outer tapering peripheral end of the ball seat into bearing engagement with the ball for preloaded increased bearing capacity and wear compensating condition and finally covering the socket-like recess at a loca tion remote from the stud projecting therefrom.

2. A method of preloading a ball joint seat retainer assembly to increase bearing capacity thereof and simultaneously providing wear compensation by steps of outward tapering an outer periphery of one end of a ball seat of acetal resin with fluorine-containing fibers mixed therein having an external cylindrical shape with tapered enlargement and a curved inner periphery at an opposite end thereof, radially slitting the ball seat longitudinally along said outward tapering location, heating the ball seat of acetal resin with fluorine-containing fibers mixed therein to a predetermined temperature to increase ductility thereof, snapping the ball axially into place complementary to the curved inner periphery with a stud carried by the ball in a location remote from said outward tapering,

pressing the ball and seat into a socket-like recess having.

a diameter less than that of the outer periphery due to said outward tapering while simultaneously urging radially inwardly the outer tapering peripheral end of the ball seat into bearing engagement with a ball for preloaded, increased bearing capacity and wear compensating condi tion, and finally covering the socket-like recess at a location remote from the stud projecting therefrom, said heating the ball seat of acetal resin with fluorine-containing fibers mixed therein occurring in a liquid medium such as lubricant at substantially F.

3. A method of preloading a ball joint seat retainer assembly to increase bearing capacity thereof and simultaneously providing wear compensation by steps of outward tapering an outer periphery of one end of a ball seat of acetal resin with polytetrafluoroethylene fibers mixed therein having an external cylindrical shape with tapered enlargement and a curved inner periphery at an opposite end thereof, radially slitting the ball seat longitudinally along said outward tapering location, heating the ball seat of acetal resin with polytetrafluoroethylene fibers mixed therein to a predetermined temperature to increase ductility thereof, snapping the ball axially into place complementary to the curved inner periphery with a stud carried by the ball in a location remote from said outward tapering, pressing the ball and seat into a socket-like recess having a diameter less than that of the outer periphery due to said outward tapering while simultaneously urging radially inwardly the outer tapering peripheral end of the ball seat into bearing engagement with the ball for preloaded, increased bearing capacity and wear compensating condition, and finally covering the socket-like recess at a location remote from the stud projecting therefrom, said slitting providing alternate deep and shallow cuts at least some of which project into the curved inner periphery of the ball seat molded of a composition of acetal resin and polytetrafiuoroethylene fibers.

References Citesl by the Examiner UNITED STATES PATENTS 1,693,748 12/1928 Fiegel et a1 29149.5 2,921,808 1/ 1960 David. 3,147,537 9/1964 Fadow.

FOREIGN PATENTS 1,118,624 11/1961 Germany.

725,724 3/ 1955 Great Britain:

CHARLIE T. MOON, Primary Examiner. 

1. A METHOD OF PRELOADING A BALL JOINT SEAT RETAINER ASSEMBLY TO INCREASE BEARING CAPACITY THEREOF AND SIMULTANEOUSLY PROVIDING WEAR COMPENSATION BY STEPS OF OUTWARD TAPERING OF AN OUTER PERIPHERY OF ONE END OF A BALL SEAT OF ACETAL RESIN WITH FLUORINE-CONTAINING FIBERS MIXED THEREIN HAVING AN EXTERNAL CYLINDRICAL SHAPE WITH TAPERED ENLARGEMENT AND A CURVED INNER PERIPHERY AT AN OPPOSITE END THEREOF, RADIALLY SLITTING THE BALL SEAT LONGITUDINALLY ALONG SAID OUTWARD TAPERING LOCATION, HEATING THE BALL SEAT OF ACETAL RESIN WITH FLUORINE CONTAINING FIBERS MIXED THEREIN TO A PREDETERMINED TEMPERATURE TO INCREASE DUCTILITY THEREOF, SNAPPING THE BALL AXIALLY INTO PLACE COMPLEMENTARY TO THE CURVED INNER PERIPHERY WITH A STUD CARRIED BY THE BALL IN A LOCATION REMOTE FROM SAID OUTWARD TAPERING, PRESSING THE BALL AND SEAT INTO A SOCKET-LIKE RECESS HAVING A DIAMETER LESS THAN THAT OF THE OUTER PERIPHERY DUE TO SAID OUTWARD TAPERING WHILE SIMULTANEOUSLY URGING RADIALLY INWARDLY THE OUTER TAPERING PERIPHERAL END OF THE BALL SEAT INTO BEARING ENGAGEMENT WITH THE BALL FOR PRELOADED INCREASED BEARING CAPACITY AND WEAR COMPENSATION CONDITION AND FINALLY COVERING THE SOCKET-LIKE RECESS AT A LOCATION REMOTE FROM THE STUD PROJECTING THEREFROM. 